Those who stayed at the ecological park were to have lived in what officials described as much better conditions.

But recently, former zoo director Claudio Bertonatti filed a complaint demanding an investigation into the deaths of Shaki and Ruth, arguing that a lack of resources and the stress from nearby construction work contributed to their demise.

"A year ago, I said that this institution was not Noah's Ark, but the Titanic on its course to be shipwrecked," Bertonatti said. "Today, we've crashed into an iceberg."

The zoo was inaugurated in 1875 on what was then a quiet patch on the outskirts of Buenos Aires. It was later a favourite haunt of Argentine novelist Jorge Luis Borges, who was fascinated by the tigers and wrote about them in his books.

But as the megalopolis grew, the zoo became surrounded by an urban sprawl of busy avenues with honking buses and screeching cars near the animal enclosures, where, on a recent day, a solitary lion spent his time chasing his tail in circles.

The antiquated enclosures were widely considered inhumane by modern standards, as were the noisy environment and pollution, and pressure from animal rights groups grew to close the zoo.

"The situation of captivity is degrading for the animals, and it's not the way to take care of them," said Buenos Aires Mayor Horacio Rodriguez Larreta when he announced the zoo's closure in 2016.

But the task remained to find new homes for the animals, hundreds of which still remain behind bars at the site in noisy limbo two years later.

Developers of the Eco Park, as the site is now called, say there have been improvements to the enclosures and the 18-hectare site has been closed to the public, reducing the stress on the animals.

About 432 of them have been transferred so far, including two grizzly bears sent to The Wild Animal Sanctuary in Colorado, three alligators to Noah's Ark Animal Sanctuary in Georgia and a Fiji crested iguana to the San Diego Zoo.

City officials acknowledge that the process of closing the zoo has proved more difficult than they originally thought. Legislation had to be enacted to set standards and authorise the transfers. Experts feared that many animals were so zoo-trained that they would die if moved, even to wild animal preserves. Other animals were not transferred because of difficult logistics - they were too large or too tall to travel.

That was the case of the giraffes: Shaki, her partner Buddy and their calf, Ciro. However, nothing indicated that Shaki was at risk of death. Giraffes in the wild live to about 25 years.

"The truth is that she was an adult female, but she had many years ahead of her," said Guillermo Wiemayer, a veterinarian who has worked at the institution for more than a decade.

Shaki began showing signs of what appeared to be abdominal pain about 9am on July 24. Six hours later, she was dead. The necropsy found an ulcer in the wall of her stomach that ultimately led to peritonitis.

It occurred just 10 days after Ruth died following an infection in her vulva that later spread. Wiemayer said the rhinoceros had been breathing heavily and had diarrhoea. She also suffered what he said were some "scratches" after she was attacked by a male rhinoceros. But overall, Ruth's condition had improved.

Then, the enclosure flooded, she slipped and got stuck in the mud. For more than six hours, her keepers made a desperate attempt to rescue her using four-wheel-drive vehicles and other machinery. By the time they got Ruth out, she was too weak.

Wiemayer denied that the deaths of the animals were related to changes in their food or stress from construction near their enclosures, saying that the work had ended months before.

"While they're under our care, we try to give them the best quality of life possible," he said near Ciro, while the young orphaned giraffe extended its long dark-grey tongue during feeding time.

"But we know that, unfortunately, we live with life and death."

The complaint filed by Bertonatti to a special unit of prosecutors that deals with environmental matters includes video showing rats and cockroaches in the enclosures of some of the park's animals.

The park's developers acknowledged that the footage was shot inside the park, but said it was years before city officials took it over in 2016. Rodents, they said, are inevitable since food is often out on the open, but they have hired a company and also got advice from a university to help them deal with infestations.

"Until the deaths of the giraffe and the rhino, there had never been criticisms in regards to the wellbeing of our animals," said Gonzalo Pascual, deputy secretary of the environment and public spaces, who is in charge of the Eco Park project, which will have interactive learning modules, green spaces and the animals that can't be transferred.

"We have more than 130 people focused on the wellbeing of the animals," he said. "Nowhere in the world do you have the amount of professionals per animal that we have here at the Eco Park."

AP